We all have times of day when we are not at our best. For me, before 10am, and between 2-4pm, it's as though my brain just doesn't work the way it should. I labor to come up with names, struggle to keep my train of thought, and my eloquence drops to the level expected of an eight-year-old.

In an effort to blame my brain for this, rather than my motivation, I reached out to a researcher in the area of sleep and circadian neuroscience. Andrea Smit, a PhD student working with Professors John McDonald and Ralph Mistlberger at Simon Fraser University in Canada, was happy to help me find excuses for why my memory is so terribly unreliable at certain times of day.

Your chronotype matters

Humans have daily biological rhythms, called circadian rhythms, which affect almost everything that we do. They inform our bodies when it is time to eat and sleep, and they dictate our ability to remember things. According to Smit, "Chronotype, the degree to which someone is a "morning lark" or a "night owl," is a manifestation of circadian rhythms.

In a recent study, Smit used EEG, a type of brain scan, to study the interaction between chronotypes and memory. "Testing extreme chronotypes at multiple times of day allowed us to compare attentional abilities and visual short term memory between morning larks and night owls. Night owls were worse at suppressing distracting visual information and had a worse visual short term memory in the morning as compared with the afternoon," she says. "Our research shows that circadian rhythms interact with memories even at very early stages of processing within the brain."

As a self-identified night owl, this is exactly what I want to hear. When someone next asks why I am being unproductive; I can say that I'm not being lazy, it's just that my brain is having trouble suppressing distracting information.

Why you need to sleep more

On top of being a night owl, I need so much sleep. I nap as if it's going out of style, and if left alarm-less I can easily turn a night's sleep into a steady 12-hour dream-a-thon.

Luckily, Smit can help with excuses here too; "Research has reliably shown that memory performance is best following an episode of sleep, and that sleep deprivation disrupts the transfer of information into long-term memory." This transfer of information into long-term memories is a process called memory consolidation (a process which I discuss at some length in my book on memory).

Smit says that this means that particularly people who need to remember information for tests or presentations "will retain more information if they get a good night's sleep." She says that this applies particularly to teenagers, opining that "school start times are too early for adolescents (who are more likely to be night owls) which negatively affects their school performance."

As a bonus high-five to sleep, Smit says that "sleep is also important for clearing away waste from the brain, including proteins whose buildup has been linked with Alzheimer's."

Being ridiculed for sleeping in? Just say something to the effect of "I didn't oversleep. I consolidated, optimized my brain for this presentation, and cleared additional waste from my brain thereby preventing the onset of Alzheimer's. What did you do this morning?" BAM.

Be careful with big schedule shifts

Watch out, however, for big changes in your sleep schedule. Disruptions to your schedule are bad news, says Smit. While many of us experience small changes to our bedtime, and some mornings we need to get up earlier than others, it's big shifts in our schedule that we need to worry about.

Shifts like those resulting from long-distance travel or shift-work. "Research suggests that circadian disruption, such as jetlag, accelerates memory loss. Chronic jetlag has been found to decrease cell proliferation and neurogenesis (the creation of new brain cells), and cause memory deficits like retrograde amnesia that last longer than the jetlag itself."

If you fancy yourself a world traveler, just make sure you get enough sleep and try not to shift your sleep schedule too many hours at a time or too often.

Research like Smit's is valuable not just to scare us into a regular schedule, but to allow us to optimize our brains. Understanding our chronotype allows us to harness times of day when we are programmed to be most efficient, and encourage us to overcome our limits (coffee!) when we need to perform at sub-optimal times of day.

Understanding the role of chronotype and sleep in memory formation also allows us to cultivate compassion for ourselves and others. It's ok that you don't like mornings. If possible, try to shift more brain-draining work to times of day when you know your brain is going to be at its best. The quality of your work and your work enjoyment will thank you.

The views expressed are those of the author(s) and are not necessarily those of Scientific American.